Egg Capsules and Early Development in Siphonarja Diemenensis (QUOY & Gaimard, 1833) And) Slphonaria Baconl (Reeve, 1856)

Summary

Spawn of two species of the littoral pulmonate genus Siphonaria from Victoria are described and found to differ only in a few minor features. Development of the two species is also similar and is followed from egglaying to hatching of a free swimming veliger phase. S.diemenensis is.in general more vigorous and develops more rapidly than S.baconi under the same conditions. Measurements of embryos and capsules at different developmental stages show that while the embryos increases in overall size from egg to hatching. the capsule Size does not alter significantly during this period.